Heavy oil and bitumen (herein also referred to as heavy hydrocarbons) are commonly moved by pipeline from the well head to a terminus which may be, for example, a refinery or a shipping port. To facilitate flow in the pipeline, a diluent is typically added to produce a hydrocarbon mixture with a viscosity suitable for pipeline transport. An advantage of pipeline transport is the relatively low cost of transport once the pipeline is installed. Disadvantages of pipeline transport are the problems of obtaining right-of-way and the initial cost of installation.
Recently, there has been interest in moving heavy hydrocarbons from the well head to a terminus by rail in special tanker cars. If moved by rail, the heavy hydrocarbon must either be heated or a diluent added to lower the viscosity so that it can be pumped in and out of the tanker cars. An advantage of rail transport is the use of pre-existing rail lines and the relatively low initial costs of acquiring special tanker cars. A disadvantage of rail transport is the somewhat higher operational cost of transport compared to pipeline transport. However this latter disadvantage can be reduced by moving heated heavy hydrocarbons rather than heavy hydrocarbons mobilized by a diluent. When a diluent is used, the volume of diluent is in the range of about 20% to about 30% of the tanker car volume, thus reducing the volume of heavy hydrocarbon that can be moved. Another disadvantage of transporting dilbit by rail is that the dilbit is liquid with a viscosity not much higher than water at outside ambient temperature. Therefore, in the event of a train derailment and rupture of some or all of the tanker cars, the spill of dibit remains liquid and must be treated as a major oil spill
In pipeline transport or rail transport using diluents, net loss of diluent is an important economic consideration since the cost per barrel of diluent is several times the cost per barrel of unrefined heavy hydrocarbon.
As described in U.S. Pat. No. 3,286,079, U.S. Pat. No. 3,372,693 and U.S. Pat. No. 4,414,462, for example, methods of transporting heated bitumen or heavy oil are known. In U.S. Pat. No. 3,286,079, a method of heating heavy hydrocarbons by resistance heaters on each car is disclosed. In U.S. Pat. No. 3,372,693, a method of heating heavy hydrocarbons by a flameless combustion heater on each car is disclosed. In U.S. Pat. No. 4,414,462, a heated railway tanker car is disclosed that includes heating conduits arranged on the tank, filled with a heating fluid and coupled to an electrically driven pump and heat exchanger in a closed-loop system for heating and continuously recirculating the heating fluid through the conduit. The tanker car is adapted to be electrically interconnected with adjacent cars and the electric power may be provided from the locomotive, from an axle generator and alternator combination on the tanker car, or from rechargeable batteries on the tanker car charged by either terminal facilities or axle-mounted or locomotive-mounted generator means. All of these prior art methods of heating heavy hydrocarbons and maintaining them within a desired temperature range require additional electrical or mechanical power supplied either by the locomotive or an auxiliary power unit.
There remains a need for a method of temperature control of heavy hydrocarbons in a consist of rail cars that does not require additional power from the locomotives or auxiliary power units for heating or cooling so that transport of hydrocarbon by rail can be practiced safely and at a per-barrel cost approaching that of pipeline transport.